inz

snmpproxy.c (raw)

/* 
 * Copyright (c) 2015 Santtu Lakkala
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 */
#include <netinet/in.h>
#include <sys/socket.h>
#include <sys/select.h>
#include <arpa/inet.h>
#include <stdlib.h>
#include <signal.h>
#include <unistd.h>
 
#include <stdio.h>
 
int running = 1;
 
void sighand(int signo)
{
	(void)signo;
	running = 0;
}
 
int main(int argc, char **argv)
{
	char buffer[8192];
	struct sockaddr_in serv = { 0 };
	struct sockaddr_in clnt = { 0 };
	struct sockaddr_in prxy = { 0 };
 
	int srv;
	int prx;
	int maxfd;
	int i;
 
	serv.sin_family = AF_INET;
	serv.sin_addr.s_addr = htonl(INADDR_ANY);
	serv.sin_port = htons(161);
 
	prxy.sin_family = AF_INET;
	inet_aton("192.168.1.1", &prxy.sin_addr);
	prxy.sin_port = htons(161);
 
	signal(SIGINT, sighand);
 
	for (i = 1; i < argc; i++) {
		if (*argv[i] == '-') {
			const char *o = &argv[i][1];
			while (*o) {
				if (i + 1 >= argc)
					return 1;
 
				switch (*o++) {
				case 'l':
					if (!inet_aton(argv[++i], &serv.sin_addr))
						return 1;
					break;
				case 'p':
					serv.sin_port = htons(atoi(argv[++i]));
					break;
				case 'd':
					if (!inet_aton(argv[++i], &prxy.sin_addr))
						return 1;
					break;
				case 'P':
					prxy.sin_port = htons(atoi(argv[++i]));
					break;
				default:
					return 1;
					break;
				}
			}
		} else {
			return 1;
		}
	}
 
	if ((maxfd = srv = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
		perror("Failed to create socket for listening: ");
		return 1;
	}
	if ((prx = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
		perror("Failed to create socket for proxying: ");
		return 1;
	}
	if (prx > maxfd)
		maxfd = prx;
 
	if (bind(srv, (const struct sockaddr *)&serv, sizeof(serv)) < 0) {
		perror("Failed to bind: ");
		return 1;
	}
 
	while (running) {
		int n;
		fd_set rfds;
		FD_ZERO(&rfds);
		FD_SET(prx, &rfds);
		FD_SET(srv, &rfds);
 
		n = select(maxfd + 1, &rfds, NULL, NULL, NULL);
 
		if (n > 0 && FD_ISSET(srv, &rfds)) {
			socklen_t len = sizeof(clnt);
			ssize_t r = recvfrom(srv, buffer, sizeof(buffer), 0,
					     (struct sockaddr *)&clnt, &len);
			if (r == 0)
				break;
			if (r > 0) {
				sendto(prx, buffer, r, 0,
				       (const struct sockaddr *)&prxy, sizeof(prxy));
				int len = (unsigned char)buffer[6];
				printf("%.*s\n", len, buffer + 7);
			}
			n--;
		}
 
		if (n > 0 && FD_ISSET(prx, &rfds)) {
			ssize_t r = recv(prx, buffer, sizeof(buffer), 0);
			if (r == 0)
				break;
			if (r > 0)
				sendto(srv, buffer, r, 0, (const struct sockaddr *)&clnt, sizeof(clnt));
		}
	}
 
	close(srv);
	close(prx);
 
	return 0;
}